Validating E-mails using message posting services

ABSTRACT

Validation of e-mails is provided. An e-mail is received. A sender of the e-mail is determined. A message posting service account that is associated with the sender is identified. The message posting service is queried for a first hash value that corresponds to the e-mail based, at least in part, on the account. A response is received from the message posting service. Whether the account includes the first hash value is determined based, at least in part, on the response. The e-mail is or is not validated based, at least in part, on the response from the message posting service.

BACKGROUND OF THE INVENTION

The present invention relates generally to the field of electronicmessaging, and more particularly to validating e-mails.

Electronic mail, most commonly referred to as email or e-mail, is amethod of exchanging digital messages from an author to one or morerecipients. Modern e-mail operates across the Internet or other computernetworks. Some early e-mail systems required the author and therecipient to both be online at the same time, in common with instantmessaging. Today's e-mail systems are based on a store-and-forwardmodel. E-mail servers accept, forward, deliver, and store messages.Neither the users nor their computers are required to be onlinesimultaneously; they need connect only briefly, typically to a mailserver, for as long as it takes to send or receive messages.

An e-mail message generally includes at least three components, themessage envelope, the message header, and the message body. The messageheader contains control information, including, minimally, anoriginator's e-mail address and one or more recipient addresses. Usuallydescriptive information is also added, such as a subject header fieldand a message submission date/time stamp.

SUMMARY

According to one embodiment of the present disclosure, a method forvalidating e-mails is provided. The method includes receiving, by one ormore computer processors, an e-mail; determining, by one or morecomputer processors, a sender of the e-mail; identifying, by one or morecomputer processors, an account of a message posting service, whereinthe account is associated with the sender; querying, by one or morecomputer processors, the message posting service for a first hash valuecorresponding to the e-mail based, at least in part, on the account;receiving, by one or more computer processors, a response from themessage posting service; determining, by one or more computerprocessors, whether the account includes the first hash value based, atleast in part, on the response; and validating, by one or more computerprocessors, the e-mail based, at least in part, on the response from themessage posting service.

According to another embodiment of the present disclosure, a computerprogram product for validating e-mails is provided. The computer programproduct comprises a computer readable storage medium and programinstructions stored on the computer readable storage medium. The programinstructions include program instructions receive an e-mail; programinstructions to determine a sender of the e-mail; program instructionsto identify an account of a message posting service, wherein the accountis associated with the sender; program instructions to query a messageposting service for a first hash value corresponding to the e-mailbased, at least in part, on the account; program instructions to,responsive to determining that the first hash value is posted to theaccount, calculate a second hash value based, at least in part, on oneor more predetermined portions of the e-mail and to compare the firsthash value and the second hash value; program instructions to,responsive to determining that the first hash value is equal to thesecond hash value, determine that the e-mail is authentic based, atleast in part, on the comparison of the first and second hash values;and program instructions to, responsive to determining that the firsthash value is not equal to the second hash value, determine that thee-mail has been tampered with.

According to another embodiment of the present disclosure, a computersystem for validating e-mails is provided. The computer system includesone or more computer processors, one or more computer readable storagemedia, and program instructions stored on the computer readable storagemedia for execution by at least one of the one or more processors. Theprogram instructions include program instructions to receive an e-mail;program instructions to determine a sender of the e-mail; programinstructions to identify an account of a message posting service,wherein the account is associated with the sender; program instructionsto query a message posting service for a first hash value correspondingto the e-mail based, at least in part, on the account; programinstructions to, responsive to determining that the first hash value isposted to the account, calculate a second hash value based, at least inpart, on one or more predetermined portions of the e-mail and to comparethe first hash value and the second hash value; program instructions to,responsive to determining that the first hash value is equal to thesecond hash value, determine that the e-mail is authentic based, atleast in part, on the comparison of the first and second hash values;and program instructions to, responsive to determining that the firsthash value is not equal to the second hash value, determine that thee-mail has been tampered with.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a computer system for validating e-mails,in accordance with an embodiment of the present disclosure.

FIG. 2 is a block diagram that depicts various transfers of informationwithin the embodiment depicted in FIG. 1, in accordance with anembodiment of the present disclosure.

FIG. 3 is a block diagram of a computer system for validating e-mails,in accordance with an embodiment of the present disclosure.

FIG. 4 is a block diagram that depicts various transfers of informationwithin the embodiment depicted in FIG. 3, in accordance with anembodiment of the present disclosure.

FIG. 5 is a block diagram that depicts various transfers of informationwithin the embodiment depicted in FIG. 3, in accordance with anembodiment of the present disclosure.

FIG. 6 depicts an example of header information of an e-mail, inaccordance with an embodiment of the present disclosure.

FIG. 7 is a flowchart that depicts operations of a mail relay server, inaccordance with an embodiment of the present disclosure.

FIG. 8 is a flowchart that depicts operations of a mail receivingdevice, in accordance with an embodiment of the present disclosure.

FIG. 9 is a block diagram of components of a computing device executingoperations for validating e-mails, in accordance with an embodiment ofthe present disclosure.

DETAILED DESCRIPTION

Embodiments of the present disclosure will now be described in detailwith reference to the drawings.

The present disclosure recognizes a need to authenticate e-mails. Ingeneral, unsolicited e-mails (i.e., spam) and spoofed e-mails are sortedout and blocked on the basis of electronic mail addresses and domainnames. Depending on various settings, however, non-spam and/or authentice-mails can be sorted out and blocked by mistake. While techniques existfor detecting falsified or spoofed e-mails (e.g., Pretty Good Privacy(PGP) and Secure/Multipurpose Internet Mail Extensions (S/MIME)), manyof these techniques require that a recipient register, and update asnecessary, at least one certificate for each trusted sender.

The present disclosure provides a mechanism for determining whether ane-mail that was transmitted over the internet has been tampered and/orspoofed. In various embodiments, it is not necessary to register andmaintain the certificates of trusted senders. In some embodiments,however, techniques such as S/MIME are used in conjunction variousaspects of the present disclosure.

Persons of ordinary skill in the art will understand that variousprotocols, such as Simple Mail Transfer Protocol (SMTP), Post OfficeProtocol (POP), and Internet Message Access Protocol (IMAP), are used totransmit electronic messages over the internet. This type of electronicmessage is hereinafter referred to as an “e-mail.” In variousembodiments, “determining whether an e-mail has been tampered with”includes not only a determination of “whether an e-mail has beentampered with” but a determination of “whether an e-mail could have beentampered with.” In addition, “determining whether an e-mail is spoofed”includes not only a determination of “whether an e-mail is spoofed” butalso a determination of “whether an e-mail could be spoofed.”

FIG. 1 depicts a block diagram of a computer system 1, in accordancewith an embodiment of the present disclosure. As shown in the figure,the computer system 1 includes a mail sending device 100, a mail relayserver 200, a mail receiving device 300, a message posting server 400,and a network 600.

The mail sending device 100 is a computer connected to the network 600and used by a sender of e-mails. The mail sending device 100 sends ane-mail addressed to the mail receiving device 300 in response to anoperation by the sender. The mail sending device 100 may be a desktop PC(personal computer), a notebook PC, a tablet PC, a PDA (personal digitalassistant), a smart phone, a cellular phone, or the like. The mail relayserver 200 is a computer that is connected to the network 600. The mailrelay server 200 relays the e-mail sent by the mail sending device 100and posts a message to the message posting server 400. The mail relayserver 200 may be a desktop PC, a workstation, or another computingdevice. In the embodiment depicted in FIG. 1, the mail sending device100 and the mail relay server 200 are within the same domain 150 toindicate that the mail relay server 200 and the mail sending device 100are owned and/or used by the same entity. In some embodiment, two ormore mail sending devices are connected to the network 600. In addition,two or more mail relay servers are connected to the network 600 in someembodiments.

The mail receiving device 300 is a computer connected to the network 600and used by a receiver of e-mails. The mail receiving device 300receives the e-mail relayed by the mail relay server 200, anddetermines, on the basis of the posted message and a time of posting,whether the e-mail has been tampered with. The mail receiving device 300may be a desktop PC, a notebook PC, a tablet PC, a PDA, smart phone,cellular phone, or another type of computing device. Is someembodiments, two or more mail receiving devices are connected to thenetwork 600.

The message posting server 400 is a computer connected to the network600 and used by a service provider to provide a message posting service.The message posting service may be a short message posting service, forexample Twitter®. In some embodiments, the message posting service hasan authentication function that uses account information, such as userIDs and passwords, to authenticate users. With the authenticationfunction, only an authenticated user can post a message. The messageposting service also records information that related to the posting ofmessages (e.g., the time and/or date of posting). In general, themessage posting service does not allow users to modify a posted message.A message can be deleted by only a user who posted the message. Invarious embodiments, messages are displayed in at least one ofhuman-readable language and machine-readable language. In someembodiments, the message posting server 400 guides the mail receivingdevice 300 to a web site to facilitate installation of plug-ins,add-ons, or other types of authentication programs that enable the mailreceiving device to determine if an e-mail has been tampered with orspoofed.

The network 600 is a set of communication lines used for informationexchange between the mail sending device 100 and the mail relay server200, between the mail relay server 200 and the mail receiving device300, between the mail relay server 200 and the message posting server400, and between the mail receiving device 300 and the message postingserver 400. The Internet is an example of the network 600.

FIG. 2 is a block diagram that depicts various transfers of informationwithin the embodiment depicted in FIG. 1, in accordance with anembodiment of the present disclosure. The mail sending device 100 sendsan e-mail addressed to the mail receiving device 300 in response to arequest of a sender of the e-mail, and the mail relay server 200receives the e-mail. The mail relay server 200 logs in to the messageposting service on the message posting server 400 using accountinformation of the sender and posts a hash value of a predeterminedportion of the e-mail to the sender's account. In one embodiment, thepredetermined portion includes the header information, the subject, andthe body of the e-mail. The message posting server 400 holds the hashvalue after recording a time of posting. In the meantime, the mail relayserver 200 sends the e-mail to the mail receiving device 300, and themail receiving device 300 receives the e-mail.

Mail receiving device 300 determines if an e-mail has been tampered withusing a plug-in (e.g., plug-in 350), an add-on, or another type ofsoftware that installed on the mail receiving device 300. Inembodiments, that include the plug-in 350 that is depicted in FIG. 2,the plug-in 350 calculates a hash value of the predetermined portion ofthe e-mail, and compares this calculated hash value with the posted hashvalue. If the hash values are different from each other, the plug-in 350determines that the e-mail has been tampered with. In some embodiments,the plug-in 350 also evaluates the difference between a time when thehash value is posted to the message posting server 400 and a time whenthe e-mail is received by the mail receiving device 300. If thedifference exceeds a time threshold set in advance, the plug-in 350determines that the e-mail has been tampered with. If the sender findsthat an e-mail has been sent in the name of the sender using an e-maildistribution list without permission, as one example of a predeterminedcondition, the sender may delete the posted message which includes thehash value from the message posting server 400. To determine whether ornot an e-mail has been spoofed, the plug-in 350 checks the sender'saccount on the message posting server 400 for the presence of the postedmessage, which includes the hash value of the predetermined portion ofthe e-mail. If the posted message does not exist in the sender'saccount, the plug-in 350 determines that the e-mail is spoofed.

A first example of a situation involving the operations described withrespect to FIG. 2 is when a broadcast e-mail is sent from a company toindividuals. In this example, the mail sending device 100 used by acompany sends an e-mail to a plurality of mail receiving devices used byindividuals via mail relay server 200. While FIG. 2 depicts a singlemail receiving device, the number of mail receiving devices is not alimitation of the present disclosure. The mail relay server 200 posts ahash value of a predetermined portion of the e-mail to a public accountof the company. Even in distribution of e-mails to a large number ofindividuals, since contents of the e-mails are the same, posting of onehash value by the mail relay server 200 is sufficient to enable the mailreceiving devices to determine whether the e-mail has been tamperedwith. If a difference between a time when the hash value is posted bythe mail relay server 200 and a time when the e-mail is received by themail receiving devices is too large, the plug-ins of the mail receivingdevices (i.e., a plurality of plug-ins 350) determine that the e-mailhas been tampered with.

A second example of a situation involving the operations described withrespect to FIG. 2 is when an e-mail is sent to individuals using aprivate mailing list. In this example, the mail relay server 200 posts ahash value of a predetermined portion of the e-mail to a private accountof the mailing list. To check the hash value posted to the privateaccount, the plug-in 350 logs in to the message posting service.

A third example of a situation involving the operations described withrespect to FIG. 2 is when an e-mail is privately sent from a company oran individual to another individual. In this case, the mail relay server200 posts a hash value of a predetermined portion of the e-mail to aprivate account of the company or the individual as a sender.

If a company is divided into a plurality of departments, a receiver mayrequest that each of the plurality of departments respectively send ane-mail with a keyword that is indicative of the department. Accordingly,even if the receiver configures a single e-mail address in a mailersoftware for receiving the e-mail, the mailer software can identify thedepartment as a sender of the e-mail, and can sort the e-mail to afolder, or another repository of information, corresponding to thedepartment if the predetermined portion includes the keyword. Since akeyword indicative of a department is added to the predetermined portionto be hashed (e.g., to header information or the body of the e-mail) thekeyword is put into the hash value posted to the private account of thecompany. Thus, even if the company has a single private account, themail receiving device 300 can identify the department as a sender of thee-mail corresponding to the hash value. In the third example describedabove with respect to FIG. 2, the receiver is an individual andtherefore allowed to assign a keyword of the receiver's choice to adepartment. The receiver may give the keyword to the department through,for example, a user interface such as a web page provided by thecompany. Since the keyword may leak in some cases, such a user interfaceenables a user to easily change the keyword. By recording a history ofkeywords, it is guaranteed that the keyword was correct at a point whenthe department was identified, even if the keyword has been changed.

FIG. 3 is a block diagram that depicts computer system 2, in accordancewith an embodiment of the present disclosure. Today, a sender of ane-mail is often entrusted with distribution of the e-mail by anentruster. In such a case, it is undesirable that the sender posts ahash value to the entruster's account without permission of theentruster. Thus, the computer system 2 is configured so that the sendercan post the hash value only when the sender is authorized by theentruster. As shown in FIG. 3, the computer system 2 includes a mailsending device 100, a mail relay server 200, a mail receiving device300, a message posting server 400, and a network 600, as described withrespect to FIG. 1. The computer system 2 also includes a mail entrustingserver 500.

The mail entrusting server 500 is a computer connected to the network600 and used by the entruster. The mail entrusting server 500 causes thehash value to be posted to the entruster's account in two manners. Inthe first manner, the mail entrusting server 500 provides the mail relayserver 200 with the entruster's account information such as theentruster's ID and password, so that the mail relay server 200 can login to the message posting service and post the hash value to theentruster's account. In the second manner, the mail entrusting server500 logs in to the message posting service using the entruster's accountinformation, and posts, to the entruster's account, the hash valuereceived from the mail relay server 200. In FIG. 3, the mail entrustingserver 500 is depicted outside the dashed line representing the boundaryof a domain 150 including the mail sending device 100 and the mail relayserver 200, but the mail entrusting server 500 is not necessarilyprovided outside the domain. In some embodiments, such as embodiments inwhich the first manner is applicable, the mail entrusting server 500 isinside the domain 150 to indicate that the mail relay server 200, themail sending device 100, and the mail entrusting server 500 are ownedand/or used by the same entity.

FIG. 4 is a block diagram that depicts various transfers of informationin accordance with embodiments where the mail relay server posts thehash value to the message posting server, in accordance with anembodiment of the present disclosure. In one example of the embodimentdepicted in FIG. 4, a broadcast e-mail is sent from an entrusted sender(e.g., an entity the controls the domain 150) to individuals. Theentruster provides the entrusted sender with the account informationincluding the entruster's ID and password of the message postingservice. The mail sending device 100 sends an e-mail addressed to themail receiving device 300 in response to a request of the entrustedsender, and the mail relay server 200 receives the e-mail. The mailrelay server 200 accesses the mail entrusting server 500 (e.g., a serverowned and/or managed by the entruster) and gets the account information.The mail relay server 200 logs in to the message posting service on themessage posting server 400 using the account information, and posts ahash value of a predetermined portion of the e-mail to the entruster'saccount. The predetermined portion includes the header information ofthe e-mail, and also includes the subject and the body of the e-mail.The message posting server 400 holds the hash value after recording atime of posting. The mail relay server 200 sends the e-mail to the mailreceiving device 300, and the mail receiving device 300 receives thee-mail.

Mail receiving device 300 determines whether or not the e-mail has beentampered with. In various embodiments, the determinations is beperformed by a plug-in, an add-on, or another type of software thatinstalled in the mail receiving device 300. To determine if the e-mailhas been tampered with, the plug-in 350 calculates a hash value of thepredetermined portion of the e-mail, and compares this calculated hashvalue with the posted hash value. If the hash values are different fromeach other, the plug-in 350 determines that the e-mail has been tamperedwith. In some embodiments, the plug-in 350 may also evaluate adifference between a time when the hash value is posted to the messageposting server 400 and a time when the e-mail is received by the mailreceiving device 300. If the difference exceeds a time threshold set inadvance, the plug-in 350 determines that the e-mail has been tamperedwith. If the entruster finds that an e-mail has been sent in the name ofthe entruster using an e-mail distribution list without permission, orthat a contract between the entruster and the entrusted sender hasexpired as examples of a predetermined condition, the entruster maydelete the posted message which includes the hash value from the messageposting server 400. To determine if an e-mail is spoofed, the plug-in350 checks the entruster's account on the message posting server 400 forthe presence of the posted message which includes the hash value of thepredetermined portion of the e-mail. If the posted message does notexist in the entruster's account, the plug-in 350 determines that thee-mail is spoofed.

FIG. 5 is a block diagram that depicts various transfers of informationin accordance with embodiments where the mail entrusting server poststhe hash value to the message posting server. In one example of theembodiment depicted in FIG. 5, a broadcast e-mail is sent from anentrusted sender to individuals. The mail sending device 100 sends ane-mail addressed to the mail receiving device 300 in response to arequest of the entrusted sender, and the mail relay server 200 receivesthe e-mail. The mail relay server 200 sends a hash value of apredetermined portion of the e-mail to an agent 550 of the mailentrusting server 500. The predetermined portion includes headerinformation of the e-mail, and also includes the subject and the body ofthe e-mail. The agent 550 logs in to the message posting service on themessage posting server 400 using account information including theentruster's ID and password of the message posting service, and poststhe hash value to the entruster's account. The message posting server400 holds the hash value after recording a time of posting. The mailrelay server 200 sends the e-mail to the mail receiving device 300, andthe mail receiving device 300 receives the e-mail.

The mail receiving device 300 determines whether or not the e-mail hasbeen tampered with. In various embodiments, the determination isperformed by a plug-in (e.g., the plug-in 350), an add-on, or type ofsoftware installed on the mail receiving device 300. To determine if thee-mail has been tampered with, the plug-in 350 calculates a hash valueof the predetermined portion of the e-mail, and compares this calculatedhash value with the posted hash value. If the hash values are differentfrom each other, the plug-in 350 determines that the e-mail has beentampered with. In some embodiments, the plug-in 350 may also evaluate adifference between a time when the hash value is posted to the messageposting server 400 and a time when the e-mail is received by the mailreceiving device 300. If the difference exceeds a time threshold set inadvance, the plug-in 350 determines that the e-mail has been tamperedwith. In the embodiment depicted in FIG. 5, upon receiving the hashvalue from the mail relay server 200, the mail entrusting server 500 maychoose not to post the hash value to the entruster's account, if theentruster finds that an e-mail corresponding to the hash value is to besent in the name of the entruster using an e-mail distribution listwithout permission, or that a contract between the entruster and theentrusted sender has expired as examples of a predetermined condition.To determine whether or not the e-mail is spoofed, the plug-in 350checks the entruster's account on the message posting server 400 for thepresence of the posted message which includes the hash value of thepredetermined portion of the e-mail. If the posted message does notexist in the entruster's account, the plug-in 350 determines that thee-mail is spoofed.

FIG. 6 depicts one example of predetermined header information, inaccordance with an embodiment of the present disclosure. In the exampledepicted in FIG. 6, each of plural Mail Transfer Agents (MTAs) whichrelay the e-mail adds data such as an identification of the device, atime of relaying and other types of data to the top of data alreadywritten by the former-stage MTA. Information in a sender data field 701indicates an identification of the mail sending device 100. Informationin a date data field 702 indicates a time when the mail sending device100 sends the e-mail. In FIG. 6, the sender data field 701 and the datedata field 702 show that the mail sending device 100 sent the e-mail atSun, 23 Mar. 2014 11:42:16 +0900 (Sun, 23 Mar. 2014 2:42:16 GMT). Arelay server data field 703 indicates an identification of the mailrelay server 200 which relays the e-mail first. A relay date data field704 indicates a time when the mail relay server 200 relays the e-mail.In FIG. 6, the relay server data field 703 and the relay date data field704 show that the mail relay server 200 relays the e-mail at Sat, 22Mar. 2014 19:42:16-0700 (Sun, 23 Mar. 2014 2:42:16 GMT). A recipientdata field 705 indicates an identification of the mail receiving device300. A Simple Mail Transfer Protocol (SMTP) server data field 706indicates an identification of an SMTP server which receives the e-mailat a stage prior to receipt of the e-mail by the mail receiving device300. A date data field 707 indicates a time when the mail receivingdevice 300 receives the e-mail. In FIG. 6, the SMTP server data field706 and the date data field 707 show that the mail receiving device 300receives the e-mail by SMTP at Sat, 22 Mar. 2014 19:43:18-0700 (Sun, 23Mar. 2014 2:43:18 GMT).

In the header information, a title and a body of the e-mail, onlyinformation within the recipient data field 705, SMTP server data field706, and date data field 707 cannot be tampered with. Only the timewhich the mail receiving device 300 adds into the header information isreliable. Each MTA other than the mail receiving device 300 can tamperwith the time of sending. Thus, it is theoretically possible to tamperwith an e-mail and post, to the message posting service, a hash valuecorresponding to the e-mail before tampering. However, the tampering isconsidered to be practically impossible in a short time of a fewminutes.

FIG. 7 is a flowchart operations of the mail relay server 200, inaccordance with an embodiment of the present disclosure.

In the embodiment depicted in FIG. 7, the mail relay server 200 receivesan e-mail that is addressed to the mail receiving device 300, which issent by a sender of the e-mail from the mail sending device 100 (step201). In some embodiments (e.g., the embodiment described with respectto FIG. 4), the mail relay server 200 receives an entruster's accountinformation in addition to the e-mail in step 201.

Mail relay server 200 adds verification data to the header informationof the e-mail (step 202). In embodiments like the one depicted in FIG.6, a time stamp in the relay date data field 704 corresponds to theverification data. Alternatively, the mail relay server 200 can addrandom characters as the verification data to the e-mail. If the plug-in350 seeks a hash value not using the verification data but using a“Date” header, the mail relay server 200 may skip this step.

Mail relay server 200 calculates a hash value of a predetermined portionincluding the header information of the e-mail (step 203).

The mail relay server 200 posts the hash value to a posting destination(step 204). In various embodiments, “posting the hash value” includes“requesting that another device post the hash value,” as described withrespect to the embodiment depicted in FIG. 5. In embodiments like theone described with respect to FIG. 2, the posting destination may be thesender's account. In embodiments like the ones described with respect toFIGS. 4 and 5, the posting destination may be the entruster's account.

Mail relay server 200 sends the e-mail (step 205).

FIG. 8 is flowchart that depicts operations of the mail receiving device300 for validating e-mails, in accordance with an embodiment of thepresent disclosure.

Mail receiving device 300 receives the e-mail sent by the mail relayserver 200 (step 301). More specifically, a mailer software of the mailreceiving device 300 receives the e-mail. The plug-in 350 monitors thee-mail to be received by the mailer software, and in response to receiptof the e-mail by the mailer software, executes various combinations ofsteps 302 to 309 to validate the e-mail, as described herein.

The plug-in 350 extracts an e-mail address from the header informationof the e-mail (step 302). In the embodiment described with respect toFIG. 2, the e-mail address may be the sender's e-mail address. In thisembodiment, the plug-in 350 extract the e-mail address from the senderdata field 701 of FIG. 6. In the embodiments described with respect toFIGS. 4 and 5, the e-mail address may be the entruster's e-mail address.In such embodiments, the plug-in 350 extracts the e-mail address from a“Reply-To” header (not shown).

The plug-in 350 identifies an account of the message posting servicecorresponding to the e-mail address (step 303). The plug-in 350identifies the account, for example, with reference to thecorrespondence table (not shown) containing a correspondence betweeneach e-mail address and an account of a user who has a correspondinge-mail address. The plug-in 350 may create and hold in advance thecorrespondence table in response to an input by a user. In theembodiments described with respect to FIGS. 4 and 5, the correspondencetable may be configured to include an account and an e-mail address ofthe entruster and not to include an account and an e-mail address of theentrusted sender. Alternatively, if the message posting service providesa function in which an account is retrieved on the basis of the e-mailaddress, the plug-in 350 may identify the account by using the function.

The plug-in 350 determines whether or not an appropriate hash valueexists in the account (step 304). In various embodiments, the plug-in350 queries the message posting server 400 to determine whether or notan appropriate hash value exists. In such embodiments, the plug-in 350receives a response from the message posting server 400, and based onthe response, determines whether an appropriate hash value is posed tothe account of the sender, as described herein. In some embodiments, theplug-in 350 seeks, as the appropriate hash value, a hash valuecorresponding to the verification data added at step 202 in FIG. 6. Inother embodiments, the plug-in 350 seeks, as the appropriate hash value,a hash value corresponding to a time of posting around a time of sendingor receipt. Note that, in some message posting services (e.g.,Twitter®), the time of posting is recorded by minutes, but it ispossible calculates elapsed seconds using tweet ID. In the headerinformation depicted in FIG. 6, the time of receipt or the time ofsending may be recorded in the date data field 702. In some embodiments,the plug-in 350 seeks messages posted within one or two minutes of atime corresponding to a “Date” header in the date data field 702, andextract a message including a hash value from the messages. In theheader information depicted in FIG. 6, the time corresponding to the“Date” header is Sun, 23 Mar. 2014 11:42:16 +0900 (Sun, 23 Mar. 20142:42:16 GMT). In this example, the plug-in 350 checks messages postedbetween Sun, 23 Mar. 2014 2:42 GMT and Sun, 23 Mar. 2014 2:43 GMT.

If an appropriate hash value does not exist in the account, the plug-in350 determines that the e-mail is spoofed (step 305).

If, at step 304, an appropriate hash value exists in the account, theplug-in 350 determines whether or not a first hash value and a secondhash value are the same (step 306). The first hash value is theappropriate hash value existing in the account. The second hash value iscalculated by hashing the predetermined portion of the e-mail. If thefirst and second hash values are not the same, the plug-in 350determines that the e-mail has been tampered with (step 307).

If, at step 306, the first and second hash values are the same, theplug-in 350 determines whether or not a difference between a first timeand a second time is less than a threshold amount of time (step 308).The first time is a time when the appropriate hash value is posted tothe account (i.e., a time of posting). The second time is a time whenthe mail receiving device 300 receives the e-mail (i.e., a time ofreceipt). If the difference between the times is not less than thethreshold amount of time, the plug-in 350 determines that the e-mail hasbeen tampered with (step 307).

If, at step 308, the difference in times is not less than the threshold,the plug-in 350 determines that the e-mail is normal/authentic (step309). Upon determining that the e-mail is authentic in this manner, thee-mail may be sorted to a folder by a sorting function.

In the flowchart depicted in FIG. 7, it is assumed that the mail relayserver 200 posts the hash value, but the operation of the mail relayserver 200 is not limited thereto. Although the mail relay server 200requests the mail entrusting server 500 to post the hash value, the mailentrusting server 500 may choose not to post the hash value to themessage posting server 400, as described with respect to the embodimentdepicted in FIG. 5. In this case, at step 304 in the flowchart of FIG.8, the plug-in 350 may also determine whether a posted message includingthe hash value does not exist in the message posting server 400 becausethe message has not been posted to the message posting server 400.Further, after the operation represented by the flowchart of FIG. 8, theposted message including the hash value may be deleted from the messageposting server 400, as explained with respect to the embodimentsdepicted in FIGS. 2 and 4. In this case, at a predetermined time afterthe operation represented by the flowchart of FIG. 8, the plug-in 350may determine whether the posted message including the hash value doesnot exist in the message posting server 400 because the message has beendeleted from the message posting server 400.

Also, in the exemplary embodiments, it is assumed that the sender of thee-mail uses a mailer software installed in the mail sending device 100and the receiver of the e-mail uses a mailer software installed in themail receiving device 300, but the present invention is not limitedthereto. Either one of the sender and the receiver may use a web e-mailsystem. The web e-mail system is an e-mail system in which e-mails canbe accessed through a web browser without installation of any mailersoftware. The present disclosure is applicable to the computer system inwhich the receiver uses the web e-mail system, on condition that abuilt-in module of the web e-mail system has functions of the plug-in350. Also, the present disclosure is applicable to the computer systemin which the sender uses the web e-mail system, on condition that thesender uses the mail relay server 200. Furthermore, the web e-mailsystem may include both of functions of the mail relay server 200 andthe built-in module.

Further, the receiver of the e-mail can check a hash value posted to themessage posting service, from a web browser. Therefore, even if aplug-in or an add-on of the mailer software is not installed, thereceiver may determine whether the e-mail has been tampered with, bymanually calculating a hash value corresponding to the e-mail.

A hash value posted to the message posting service may be tampered within some cases. In such cases, the hash value may be posted to pluralmessage posting services (e.g., Twitter® and other services). This makesit possible to find, in any of the plural message posting services, thehash value which has not been tampered with.

FIG. 9 depicts computer system 900. Computer system 900 is an example ofa system that is capable of executing the plug-in 350. Computer system900 includes communications fabric 902, which provides communicationsbetween computer processor(s) 904, memory 906, persistent storage 908,communications unit 910, and input/output (I/O) interface(s) 912.Communications fabric 902 can be implemented with any architecturedesigned for passing data and/or control information between processors(such as microprocessors, communications and network processors, etc.),system memory, peripheral devices, and any other hardware componentswithin a system. For example, communications fabric 902 can beimplemented with one or more buses.

Memory 906 and persistent storage 908 are computer readable storagemedia. In this embodiment, memory 906 includes random access memory(RAM). In general, memory 906 can include any suitable volatile ornon-volatile computer readable storage media. Cache 916 is a fast memorythat enhances the performance of processors 904 by holding recentlyaccessed data and data near accessed data from memory 906.

Program instructions and data used to practice embodiments of thepresent invention may be stored in persistent storage 908 for executionby one or more of the respective processors 904 via cache 916 and one ormore memories of memory 906. In an embodiment, persistent storage 908includes a magnetic hard disk drive. Alternatively, or in addition to amagnetic hard disk drive, persistent storage 908 can include a solidstate hard drive, a semiconductor storage device, read-only memory(ROM), erasable programmable read-only memory (EPROM), flash memory, orany other computer readable storage media that is capable of storingprogram instructions or digital information.

The media used by persistent storage 908 may also be removable. Forexample, a removable hard drive may be used for persistent storage 908.Other examples include optical and magnetic disks, thumb drives, andsmart cards that are inserted into a drive for transfer onto anothercomputer readable storage medium that is also part of persistent storage908.

Communications unit 910, in these examples, provides for communicationswith other data processing systems or devices. In these examples,communications unit 910 includes one or more network interface cards.Communications unit 910 may provide communications through the use ofeither or both physical and wireless communications links. Programinstructions and data used to practice embodiments of the presentinvention may be downloaded to persistent storage 908 throughcommunications unit 910.

I/O interface(s) 912 allows for input and output of data with otherdevices that may be connected to each computer system. For example, I/Ointerface 912 may provide a connection to external devices 918 such as akeyboard, keypad, a touch screen, and/or some other suitable inputdevice. External devices 918 can also include portable computer readablestorage media such as, for example, thumb drives, portable optical ormagnetic disks, and memory cards. Software and data used to practiceembodiments of the present invention can be stored on such portablecomputer readable storage media and can be loaded onto persistentstorage 908 via I/O interface(s) 912. I/O interface(s) 912 also connectto a display 920.

Display 920 provides a mechanism to display data to a user and may be,for example, a computer monitor.

The present invention may be a system, a method, and/or a computerprogram product. The computer program product may include a computerreadable storage medium (or media) having computer readable programinstructions thereon for causing a processor to carry out aspects of thepresent invention.

The computer readable storage medium can be a tangible device that canretain and store instructions for use by an instruction executiondevice. The computer readable storage medium may be, for example, but isnot limited to, an electronic storage device, a magnetic storage device,an optical storage device, an electromagnetic storage device, asemiconductor storage device, or any suitable combination of theforegoing. A non-exhaustive list of more specific examples of thecomputer readable storage medium includes the following: a portablecomputer diskette, a hard disk, a random access memory (RAM), aread-only memory (ROM), an erasable programmable read-only memory (EPROMor Flash memory), a static random access memory (SRAM), a portablecompact disc read-only memory (CD-ROM), a digital versatile disk (DVD),a memory stick, a floppy disk, a mechanically encoded device such aspunch-cards or raised structures in a groove having instructionsrecorded thereon, and any suitable combination of the foregoing. Acomputer readable storage medium, as used herein, is not to be construedas being transitory signals per se, such as radio waves or other freelypropagating electromagnetic waves, electromagnetic waves propagatingthrough a waveguide or other transmission media (e.g., light pulsespassing through a fiber-optic cable), or electrical signals transmittedthrough a wire.

Computer readable program instructions described herein can bedownloaded to respective computing/processing devices from a computerreadable storage medium or to an external computer or external storagedevice via a network, for example, the Internet, a local area network, awide area network and/or a wireless network. The network may comprisecopper transmission cables, optical transmission fibers, wirelesstransmission, routers, firewalls, switches, gateway computers and/oredge servers. A network adapter card or network interface in eachcomputing/processing device receives computer readable programinstructions from the network and forwards the computer readable programinstructions for storage in a computer readable storage medium withinthe respective computing/processing device.

Computer readable program instructions for carrying out operations ofthe present invention may be assembler instructions,instruction-set-architecture (ISA) instructions, machine instructions,machine dependent instructions, microcode, firmware instructions,state-setting data, or either source code or object code written in anycombination of one or more programming languages, including an objectoriented programming language such as Smalltalk, C++ or the like, andconventional procedural programming languages, such as the “C”programming language or similar programming languages. The computerreadable program instructions may execute entirely on the user'scomputer, partly on the user's computer, as a stand-alone softwarepackage, partly on the user's computer and partly on a remote computeror entirely on the remote computer or server. In the latter scenario,the remote computer may be connected to the user's computer through anytype of network, including a local area network (LAN) or a wide areanetwork (WAN), or the connection may be made to an external computer(for example, through the Internet using an Internet Service Provider).In some embodiments, electronic circuitry including, for example,programmable logic circuitry, field-programmable gate arrays (FPGA), orprogrammable logic arrays (PLA) may execute the computer readableprogram instructions by utilizing state information of the computerreadable program instructions to personalize the electronic circuitry,in order to perform aspects of the present invention.

Aspects of the present invention are described herein with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems), and computer program products according to embodiments of theinvention. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer readable program instructions.

These computer readable program instructions may be provided to aprocessor of a general purpose computer, special purpose computer, orother programmable data processing apparatus to produce a machine, suchthat the instructions, which execute via the processor of the computeror other programmable data processing apparatus, create means forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks. These computer readable program instructionsmay also be stored in a computer readable storage medium that can directa computer, a programmable data processing apparatus, and/or otherdevices to function in a particular manner, such that the computerreadable storage medium having instructions stored therein comprises anarticle of manufacture including instructions which implement aspects ofthe function/act specified in the flowchart and/or block diagram blockor blocks.

The computer readable program instructions may also be loaded onto acomputer, other programmable data processing apparatus, or other deviceto cause a series of operational steps to be performed on the computer,other programmable apparatus or other device to produce a computerimplemented process, such that the instructions which execute on thecomputer, other programmable apparatus, or other device implement thefunctions/acts specified in the flowchart and/or block diagram block orblocks.

The flowchart and block diagrams in the Figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods, and computer program products according to variousembodiments of the present invention. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof instructions, which comprises one or more executable instructions forimplementing the specified logical function(s). In some alternativeimplementations, the functions noted in the block may occur out of theorder noted in the Figures. For example, two blocks shown in successionmay, in fact, be executed substantially concurrently, or the blocks maysometimes be executed in the reverse order, depending upon thefunctionality involved. It will also be noted that each block of theblock diagrams and/or flowchart illustration, and combinations of blocksin the block diagrams and/or flowchart illustration, can be implementedby special purpose hardware-based systems that perform the specifiedfunctions or acts or carry out combinations of special purpose hardwareand computer instructions.

The term(s) “Smalltalk” and the like may be subject to trademark rightsin various jurisdictions throughout the world and are used here only inreference to the products or services properly denominated by the marksto the extent that such trademark rights may exist.

The descriptions of the various embodiments of the present inventionhave been presented for purposes of illustration, but are not intendedto be exhaustive or limited to the embodiments disclosed. Manymodifications and variations will be apparent to those of ordinary skillin the art without departing from the scope and spirit of the invention.The terminology used herein was chosen to best explain the principles ofthe embodiment, the practical application or technical improvement overtechnologies found in the marketplace, or to enable others of ordinaryskill in the art to understand the embodiments disclosed herein.

What is claimed is:
 1. A method for validating e-mails, the methodcomprising: receiving, by one or more computer processors, an e-mail;determining, by one or more computer processors, a sender of the e-mail;identifying, by one or more computer processors, an account of a messageposting service, wherein the account is associated with the sender;querying, by one or more computer processors, the message postingservice for a first hash value corresponding to the e-mail based, atleast in part, on the account; receiving, by one or more computerprocessors, a response from the message posting service; determining, byone or more computer processors, whether the account includes the firsthash value based, at least in part, on the response; validating, by oneor more computer processors, the e-mail based, at least in part, on theresponse from the message posting service determining, by one or morecomputer processors, a time of receipt of the e-mail; determining, byone or more computer processors, a time of posting of the first hashvalue; and determining, by one or more computer processors, a durationof time between the time of receipt and the time of posting.
 2. Themethod of claim 1, wherein validating the e-mail comprises: in responseto determining that the account includes the first hash value,calculating, by one or more computer processors, a second hash valuebased, at least in part, on one or more predetermined portions of thee-mail; and determining, by one or more computer processors, that thefirst hash value is equal to the second hash value, and, in response,determining, by one or more computer processors, that the e-mail isauthentic.
 3. The method of claim 1, wherein validating the e-mailcomprises: in response to determining that the account includes thefirst hash value, calculating, by one or more computer processors, asecond hash value based, at least in part, on one or more predeterminedportions of the e-mail; and determining, by one or more computerprocessors, that the first hash value is not equal to the second hashvalue, and, in response, determining, by one or more computerprocessors, that the e-mail has been tampered with.
 4. The method ofclaim 1, wherein the first hash value is posted to the message postingservice via the account associated with the sender, and wherein thefirst hash value is based, at least in part, on the one or morepredetermined portions of the e-mail.
 5. The method of claim 1, whereinquerying the message posting service for the first hash value is based,at least in part, on verification data contained in the e-mail.
 6. Themethod of claim 1, wherein querying the message posting service for thefirst hash value is based, at least in part, on a time of receipt of thee-mail.
 7. The method of claim 1, wherein validating the e-mailcomprises: determining, by one or more computer processors, that thefirst hash value is not posted to the account based on a response toquerying the message posting service and, in response, determining, byone or more computer processors, that the e-mail is spoofed.
 8. Themethod of claim 1, wherein validating the e-mail comprises: determining,by one or more computer processors, that the first hash value is equalto the second hash value; determining, by one or more computerprocessors, that the duration of time between the time of receipt andthe time of posting is less than a threshold duration of time; anddetermining, by one or more computer processors, that the e-mail isauthentic.
 9. The method of claim 1, wherein validating the e-mailcomprises: responsive to determining, by one or more computerprocessors, that the duration of time between the time of receipt andthe time of posting is equal to or greater than the threshold durationof time, determining, by one or more computer processors, that thee-mail has been tampered with.